Answer:
0.017 moles of ammonia remains after the reaction is stopped.
Explanation:
The reaction is:
4NH₃ + 5O₂ → 4NO + 6H₂O
The first step is to convert the mass to moles, of each reactant:
2 g . 1mol/ 17g = 0.117 moles of NH₃
4 g . 1mol /32g = 0.125 moles of O₂
Ammonia, states the question, is the excess reactant so we can confirm it,
5 moles of oxygen need 4 moles of ammonia to react (by stoichiometry)
Then, 0.125 moles of oxygen may react to (0.125 . 4) / 5 = 0.1 moles
As we have 0.117 moles of ammonia and we need 0.1 moles.
(0.117 - 0.1) = 0.017 moles remains after the reaction is completed.
If we convert the moles to mass we have:
0.017 mol . 17 g /1mol = 0.289 g
